This research will explore the language learning process in preschool children with specific language impairments to determine whether there are optimum times for providing direct treatment. Specifically this study will examine linguistic variables predicting whether language impaired children will differentially benefit from direct treatment designed to facilitate the acquisition of two-word relational utterances. Through dynamic assessment procedures, children's potential for linguistic growth (i.e., level of stimulability) will be examined. Determining how responsive, or how stimulable, a child is, will indicate if treatment can serve to either induce the emergence of new language behaviors, or accelerate the mastery of inconsistent ones. In this research stimulability characteristics of preschool, language-impaired children at the one-word stage will be explored according to how well they predict the benefits of treatment provided directly by a speech/language pathologist. Two experiments will be conducted. Experiment I will employ a between groups design to examine the differential learning of children who have been categorized through dynamic assessment procedures as being either high stimulable, moderately stimulable or low stimulable for the acquisition of particular two-word utterance types. Experiment II will employ a within subject design to examine how individual subjects acquire particular two- word utterance types that have been identified as being high stimulable, moderately stimulable or not stimulable. Predicting the benefits of language treatment implies that the acquisition process cannot proceed by maturation alone. To explore this issue, both experiments will examine children's magnitude and rate of learning treated versus untreated (control) utterance types. The outcome of this research will shed light on the language acquisition process and provide guidelines for clinical decisions regarding "who to treat and when".